A. Technical Field
The present invention relates to a process for culturing animal cells obtained from living body tissue. More particularly, the invention relates to a process for culturing animal cells obtained from living body tissue in order to use them for further culture and/or a test.
B. Background Art
Anticancer agent sensitivity tests sometimes have been carried out using subcultured cancer cells hitherto, but for the purpose of evaluating effects of anticancer agents upon respective individuals, methods of evaluating the effects of the anticancer agents by utilizing so-called primary culture, in which samples taken from a living body are directly cultured, are widely employed. However, when cancer cells were taken from living body tissue as a sample and then used, there were problems such that: a necessary and sufficient amount of live cells maintaining proliferativity cannot be obtained, and in addition, the sample contains normal cells other than the aimed cancer cells, and further contains many other components such as bacteria.
Accordingly, as a method for efficiently carrying out anticancer agent sensitivity tests, for example, the following method has been applied in recent year: a method in which primary cells containing cancer cells in a collagen gel is embedded, and then cultured. Even if the absolute amount of the cancer cells as used for the tests is small, the cancer cells can favorably be proliferated in the collagen gel. In addition, even if the collagen gel is contaminated with cells other than the cancer cells such as fibroblast cells and each is grown and extended, they can easily be distinguished morphologically. Therefore, the evaluation of the sensitivity of only the cancer cells both the anticancer agents are added thereto and not can easily be carried out.
Furthermore, for the purpose of enhancing the accuracy of the tests, well known is a method that involves: placing a droplet of a cancer-cell-containing collagen solution on a surface of a supporting base material; allowing the droplet to gel; and forming and embedding a globular collagen gel, in order to culture the cancer cells under more favorable density and circumstances to proliferated the cancer cells more easily (Japanese Patent No. 2879978).
These methods may be theoretically and technically preferred, but, when such as anticancer agent sensitivity tests are carried out using cells sampled for biopsy as actually sampled from living bodies, the test success rate is still low, and the level of the tests is not sufficient to say that it is in on a realistic and practical level in the clinical. As to its cause, the following is mentioned first: there are many cases where cells of which the number has a level such that the test can sufficiently be carried out cannot be collected, or the cells cannot be collected at all. In order to solve this, it is thought necessary to reduce the loss of the number of the cells as sampled from the living bodies as low as possible. However, the washing step regarded as necessary in conventional methods has problems such that: it is very difficult to carry out the step for a very slight sample amount of biopsy materials; the sufficient washing is impossible; and further the yield is very low and the loss is increased. As to the second cause, the following is mentioned: the culture cannot be continued often because of the contamination with such as bacteria. It is natural to cause the possibility of the contamination on the operation, and tissue sampled in vivo especially from such as intestines includes Escherichia coli and various bacteria that are bacteria ordinary living in vivo. Therefore, under the present circumstances, even if the process of the above-mentioned washing step is gone through, the inhibition of the contamination still cannot entirely be performed, resulting in serious problems.